The dynamic of light and human health has been studied for years—and never so much as in the last decade. Discussions of how lighting affects our health are not limited to scientists or lighting design professionals; it’s become mainstream knowledge that light triggers our circadian system for good or bad.
We know daylight is good for us and that it sets our circadian system for the 24-hour clock, especially in the morning hours when blue light waves are prevalent. Blue light at night—including light from electronic devices such as televisions, tablets, and phones—is known to interrupt the circadian system by preventing the activation of melatonin that helps move our systems toward sleep.
Programs such as the WELL Building Standards focus on creating a sense of well-being for people working primarily in commercial and industrial sectors. Lighting has become a key part of the discussion because most of an employee’s daylight hours are spent indoors. For some, electric sources may provide the only light they experience in 24 hours.
We live and work in a 24/7 world with corporations allowing flexible work hours well beyond the 9-5 day. It’s not just the shift-worker that may be going to and from work in darkness. For some, it may be a preferred or family-necessary schedule. For many, the winter months include a commute to work in darkness and then home again in darkness. We need to consider how we light interior commercial spaces at night as much as for day use. Not everyone has access to daylight in their workspace, and many don’t sit next to a window where daylight can help support circadian health.
At the recent Illuminating Engineering Society (IES) Light and Human Health Symposium in Atlanta, Dr. Mariana Figuerio, director of the Lighting Reach Center and Light and Health program director, reported that only those people sitting directly next to windows receive benefits of circadian stimulus from daylight and only when faced looking directly out of the window.
Most people now know that light and the color of light—more specifically, the spectral power distribution or wave length—affect our circadian internal clock. Media presentations have focused on reducing or eliminating blue light at night. Color-changing “tunable white light” sources are being promoted for schools, office buildings, and healthcare institutions. While most designs/implementations focus on the tunable white element, many do not also take into consideration the other elements required to support circadian rhythm: spectral power distribution (wave length), timing (24-hour clock), light history (prior exposure to light), spatial distribution (direction of light source), and intensity (brightness). All must be present to support our circadian well-being.